Dry lubricant ball-type bearing with non-rotating balls



Aug- 28, 1962 R. v. KLINT ETAL 3,05l,535.

DRY LUBR .777 ven 'or-'sz' Robert 1/. K/fnt, Faber-' 8. Owens,

DRY LUBRICANT BALLTYPE BEARING WITH NON-ROTATING BALLS Robert V. Kiint, Rexford, and Robert S. Owens, Watervliet, N.Y., assignors to General Electric Company, a corporation of New York Filed Nov. 20, 1959, Ser. No. 854,391 14 Clairns. (Cl. 308-240) This invention relates to a dry lubricant ball-type bearing with non-rotating 'balls and, more particularly, to such a bearing utilizing a dry lubricant and operating on the principle of sliding friction.

With the advance of modern technology of bearings towards Operating limits of increased temperature and load carrying ability, the field of lubrication has also been advanced to include these Operating parameters more importantly, various types of lubrication are -becoming necessary to meet the existing and sometimes limiting lubrication requirements. A particular type of lubricant to which this invention in one form is directed, is a solid or dry lubricant as ditferentiated from liquid and/or grease-type lubricants. Certain inorganic compounds, i.e., the sulfides, disulfides, selenides and tellurides of such metals as molybdenum, tungsten, titanium, and uranium are characterized by a laminated or plate-like crystal structure in which the metallic atoms are arranged in a single common plane While the non-metallic atoms are attached to the metallic atoms to' form layers on both sides of the plane. The non-metallic atoms in each of the crystals in the Sandwich structure have very little attraction for each other so that the crystals will slip readily with respect to each other under the action of low shearing forces. Moreover, the non-metallic atoms have an affinity for adjacent metal surfaces so that the crystals attached to such surfaces will exhibit very strong resistance to the action of forces normal to the direction of the shear. Consequently, these compounds have excellent lubricating properties and also have excellent antiseizing properties. A Well known and promising lubricant is molybdenum disulfide (M082). It has been found, however, that M082 alone has several inherent disadvantages as a dry lubricant, including, first, M052 has a high wear rate and thus wears quite rapidly with continual replenishment being necessary. Second, as the M052 wears, large amounts of this material are accumulated between moving surfaces and may in some instances cause jamming or other undesirable effects. Furthermore, M082 has a poor load carrying ability and its use is thereby restricted to light application. Accordingly, in copending application Serial No. 830,482, Oliver and Haltner, filed July 30, 1959, now abandoned, and assigned to the same assignee as the present invention, there has been disclosed and claimed, certain additives to be included in a lubricant together with M052 and which overcomes these aforementioned problems. Such additives are given as taken from the class consisting of SnS2, Sb2S5, CaS, BaS, CdS, Cr2S3, Ag2S, and Bi2S2. However, for the lpurpose of this invention, other additives may 'be combined with M052 and also various dry lubricants in addition to the M082 and the MS2 combinations may be employed. The aforementioned application is incorporated by reference herewith.

Experience has shown that the most practical use for a solid lubricant is as a surface film on one or both of generally metallic surfaces to be lubricated. Commercial preparations which are widely used, employ organic resins to bond the solid lubricant to the given surface. The presence of the organic material, of course, alters the properties of the film. Usually, the thermal resistance of the 'binder faHs far short of that of the inorganic solid minute.

lubricant, thus imposing a high temperature limit on the usefulness of the film which is lower than that of the lubricant itself. Furthermore, the load carrying ability of ythese resin bonded films under severe conditions is less than desired.

One problem encountered in certain applications, when using the lubricant in the aforementioned copending application (Serial No. 830,482), relates to the means of attaching the film or coating to a given surface and to thereafter obtain effective utilization of the dry lubricant. In copending application Serial No. 830,481, Haltner and Oliver, filed July 30, '1959, and assigned to the same assignee as the present invention, there lis disclosed and claimed a novel method of applying a satisfactory dry lubricant to a given surface. In the practice of the invention of that application, a suitable lubricant film is applied, in one instance, to a surface of a shaft where the shaft may be mounted in, for example, a lathe or other similar rotating apparatus, and thereafter a small diameter pellet of the lubricant material, suitably attached to a holder, is forced against the shaft and moves along the shaft to provide a film of the desired width. Only a few [passes along the shaft are necessary, since a maximum lbuild-up of the lubricant film is soon reached and no additional benefit is gained by fuither application. Best results Were obtained in practicing that invention upon meals, for example, `chromium, cast iron, and stainless steels. However, a preferred sub-surface to a lubricant filmwhere the lubricant is taken from the aforementioned copending application Serial No. 830,482, has been chromium, which is crack-free, generally impervious and retained in a clean state free of surface contaminations,

' oxides, impurities, etc., until just prior to the application of the film. A specific example was the application of M082, with the various additives, applied to a chromium plate. The pellet was zz molykote microsize MoS2 of about a 2716 inch diameter with an applied load of 2 kilograms. It was rubbed on a plate with a speed of about 100 feet per Similar tests were made on M082 containing an additive of about 10 percent, by weight of the total, of SnS2 and carried a load of 6.1 kilograrns of an 1/8 inch diameter steel ball with the lubricant film remaining intact. It was discovered that the lubricant film on a metal may 'be improved by burnishing the film. For example, a film acquired on a chromium surface as described is lightly burnished by a steel ball in the same manner as i the term burnishing is generally applied to metal working. The steel ball is pressed into the chromium surface sufficiently to very lightly metal work the chromium and one pass is made across the film. Two included benefits of this burnishing action appeared, a Stronger bond :between the M052 and the metal is Produced and the burnishing provides a thin, smooth film having Optimum frictional properties. The disclosure of the latter application (830,481) is incorporated by reference herein.

Optimum benefits are therefore obtained with the dry lubricant and the method of attaching the same as taught in the prior mentioned applications. In some circumstances, however, less friction and longer operation are desirable, but longer operation requires a repetition of the bearing makeup process with additional burnishing. Less friction requires a modification of the bearing surfaces. Together with less friction and longer operation, there is a constant demand for a more economical bearing, one easily and quick'ly maintained, one where bearing clearance is at a minimum, and also' short term expendable bearings.

It has been discovered that the teachings of both the aforementioned applications may be combined into a unique, novel, and hithertofore unknown bearing configuration which combines the best advantages of the two and which have relative motion.

-prior applications, extends their applicable ranges and provides, at the same time, means overcorning the discussed problems of less friction, longer operation, greater economy, less clearance together with various bearing problems well known to those ski'lled in the art.

Accordingly, it is an object of this invention to provide an improved method of using a dry lubricant.

It is another object of this invention to provide-an improved dry lubricant bearing.

It is another object of this invention to provide continual replenishing and 'burnishing of a dry lubricant in a bearing.

It is another object of this invention'to provide a low coefiicient of friction dry lubricant sliding bearing.

It is another object of this invention to provide an economical bearing for high temperature operation.

It is yet another object of this invention to provide a dry lubricant'lubricated non-rotating type of ball bearing.

These and other objects, features and advantagesof this invention are attained by the use of, in one example, a ball-type of bearing having a minimum number of balls wherein the balls are of the non-rotating variety and slide on a dry lubricant film which is being continuously burnished.

This invention Will be better understood when taken in connection with the following description and the drawing in which:

PIG. 1 is an exemplary form of a non-rotating, balltype bearing;

FIG. 2 is a sectional view of FIG. 1 taken on the line 2-2;

FIG. 3 is a modification of the bearing illustrated-in FIG. 1;

=FIG. 4 is a modification of the bearing illustrated in FIG. 1; and

FIG. 5 is another modification of the bearing illustrated in FIG. 1.

Referring now to FIG. 1, there is shown one exemplary ball-bearing made in accordance 'with the teachings of this invention.

This application proceeds with an exemplary description relating to a modified ball-type bearing. The invention is applicable to various types of bearings, including thrust bearings, where two bearing surfaces are provided This motion maybe rotary, reciprocatory or various combinations thereof, and one or both surfaces may move. It is also contemplated that the bearing apparatus or means may be incorporated with either surface.

In FIG. 1, bearing includes an outer support member, housing or ring 11 which may be in an electric motor, for example, the bearing housing in the end bells. Included within the housing or outer ring 11 is a mem- 'ber 12 generally of a metallic nature, for example, steel,

e and which includes an arcuate surface v14. Member 12 may be of a set screw variety or non-threaded and pressed into or suitably locked in opening 13. Spaced l20 cirmanner as member-12. lSpac'ed circumferentially120 from member 15 is an additional member 17.f VMember 17 is biased radially inwardly by means of -a spring 18 'or any other form of resilient or biasing meansV suitable under the circumstances. While member '17 i shown as 'being biased from housing 11,` it is'understood -'that= if the housing 11 is an integral part of the'bearing structure, then spring or biasing means 18 may depend from orrbe aflixed to the housing in which the' bearing is to be positioned.V Member 17, however, is a dry lubricant material taken from any of the examples as g'ivenfin the afo'rementioned application Serial No. 8302482," for example, a pressed pellet of a'MoS2-SnS2 mixture.

' be chrome.

surface.

shaft 19 is coaxially positioned between the three members 12, 15- and 17 for rotation therebetween.

'Referring now to FIG. 2, shaft 19 is illustrated as having a chrome plating 20 thereon, on the surfaces which are to be engaged by members 12, 15 and 17. Such a chrome s'urfacing 20 'may be a plating, a sleeve, or any other method of providing a chrome surface ona given shaft, although it is'understood that the shaft 'itself may While the shaft 19 may be of various materials, best results are obtained when the shaft is of a hard metal, for example steel. "When-a chrome plating is employed, a hard steel shaft permits a thin coating. If the base surface is soft sheel, a tbicker plated surface is desirable.

In the first instance, it is understood that this bearing, by incorporating the solid lubricant as indicated in copending application Serial No. 830,482, derives all the advantages associated with the Vuse of such a lubricant. In addition, the dry lubricant of the member 17 is utilized to its optimum advantage in accordance with the teachings of copending .application Serial No. 830,481, Le., providing a film of the preferred lubricant on a chrome-plated shaft. Thereafter, in the second instance, the optimum advantage of copending application Serial No. 830,481 is obtained by the use of members 12 and 15 which =burnish the lubricant film being applied to the chrome Further advantages have been Vdiscovered in that bearing characteristics are improved by arcuate surface contact or substantially line contact during operation, and that ltogether with much higher loadings on the film, the coeflicient of friction is reduced. It is also interesting to note that with'biasng of member 17, there'is presented a bearing configuration in which tolerances are substantially reduced to zero.

The positioning of the bearing may be varied to suit various apparatus mountings. For example, the bearing as a unit may be rotated such that the biased solid lu- 'bricant member 17 may take any circumferential position. Biasing may be employed for all or any number of the members 12, 15 and 17. It is understood, of course, that more members 12 and 15 or less, may be employed, and in all instances the circumferential spacing may be varied or be unequal spacings.

'An exemplary modification is illustrated in FIGS. 3 and 4 which combined -illustrate a bearin-g having a spherical element 23 directly under a shaft. The lubricant for this modification is illustrated in FIG. 3 as acylindri- Vcal element 21 suitably biased by springV 22.

Refern'ng now to FIG. 4, there is also shown one method of mounting a sliding element in the form of a steel ball 23, in a ring 11. This modification was employed for test purposes with good results. Ring `11 has an opening 24' therein which provides projection of a portion' of the ball from the ring while retaining the ball within the ring. Thereafter, the ring material is peened or crimped as at 25 to lretain the ball fixedly in place.

Referring now to FIG. 5, there is illustrated a modiffication in the form of 'an annular ring member 27 which could be -foi'med as a part of the apparatus bearing housing, but which in preferred form, is a separate ring to be lpositioned within a housing. Annular ring 27 has 'an interior surface 20 which is generallyarcuate to provide la line contact with shaft 19. A suitable biased pelletiof lubricant material 29 is provided 'within ring member 27 in -an opening 30 -therein It is understood that in the operation of this type bearing that dry lurbicant is being continually supplied by means of pellet 29 on a chromeplated shaft while thereafter the internal lsurface vof the ring 27 provides continual light burnishing and substan- Atially line contact or very narrow surface contact with sliding friction. It is obvious that ring 27 |could be segmental and suitably biased.

for linear bearings having a moveable element therein. Specific examples of bearings made in accordance with the teachings of this application and their operating condition is given as follows:

Example 1 A series of tests were made on a bearing configuration employing a single 1A inch diameter steel ball 'and a lubricant pellet spaced less than 180 therefrom counter to the direction of rotation. The 'bearing was suspended from a shaft Iand weights attached thereto. The shaft was g a hard steel shaft 1/2V inch diameter With a chrome plating Example 2 A series of tests were made on the 'bearing configuration of FIG. 1 where two steel balls and a pellet were employed, in 120" 'spacings In these tests, all conditions were similar. A MoSz-SnSz pellet was used, 90% and by weight, `respectively. Coefficient of -friction Was found lto be .about 0.1.

Example 3 The configuration em ployed in this example employed three steel balls positioned 120 apart with a lubricant pellet between the top ball and the next adjacent opposite the direction of rotation. Operating parameters were the same as for Example 1. A MoS2-AgS2 pellet 90% and 10%, by Weight, respectively, was used. Coeicient of friction was about 0.1.

It can thus be understood that by means of the teachings of this invention that there is provided, a nonrotating or sliding type of ball bea-iing which is economical, easily assembled, and having, therefore, wide applica-bility; also, a bearing is provided which incorporates a dry lubricant for all of a dry lubricant's advantages of high temperature operation. The coefiicient of frietion is reasonable for various applications where liquid or grease lubrication is neither satisfactory nor desirable, or where accessibility is difficult. These advantages taken with the continual lubricant replenishment burnishing aspect represents a lgreatly improved bearing for a host of applications requiring the overcoming of difliculties before discussed.

It is aiso to be understood that such a bearing withstands very high loadings on the arcuate contact surface (substantially line contact when sliding) with reduced friction and less tendency for jamming. Furthermore, the line contact principle can be equally utilized in helical form, for example, Where a helix is formed on the shaft surface with some clearance in the housing.

While 'a specific method and apparatus in accordance with this invention has been shown and described, it is not desired that the invention be limited to the particular description nor to the particular configurations i-llustrated, and it is intended by the appended claims to cover all modifications vvithin the spirit and scope of this invention.

What we claim as new 'and desire to secure by Letters Patent of 'the United States is:

1. A uni'tary -bearing comprising in combination a support member, a moveable element positioned for movement in said support member to define adjacent bearing surfaces, a dry lubricant film on one of said surfaces, means providing additional dry lubricant to said one surface, at least one fixed arcuate surface on the other of said surfaces engaging the said one of said surfaces so that sliding bearing action takes place defining substantially line contact between the 'arcuate surface and the said one suiface on said film.

2. A sliding bearing comprising in combination, a support member wherein an element is positioned to provide bearing surfaces, means positioning a sliding member having a curved surface thereon to slidably engage one of said surfaces, 'said sliding member describing upon relative movement of 'said surfaces substantially line contact, and .means providing a dry lubricant member engaging the said one of said surfaces and spaced from said sliding member, biasing means lbiasing said lubricant member against said surface so that upon movement of said element a 'film of lubricant is continually applied to the said surface and lightly burnished by said sliding member to provide a bearing.

3. A rotary sliding bearing comprising in combination, a support member wherein a shaft is positioned to rotate, at 'least one sliding member having a curved surface thereon fixed in said support to engage said shaft, said sliding member maintaini-ng said shaft in spaced relationship to said support, said sliding member describing upon rotation of said shaft substantially line contact, at least one dry lubricant memfber positioned in said support and spaced circumferentially from said sliding member, biasing means biasing said lubricant member against said shaft so that upon rotation of said shaft a film of lubricant is 'continually applied to said shaft and lightly burnished by said sliding member to provide a bearing.

4. A 'rotary sliding bearing comprising in combination, a support member wherein va hard steel shaft is positioned to rotate, at least one sliding steel member *having a curved surface thereon fixed in said support to engage said shaft, said sliding member maintaining said shaft in spaced relationship to said support, said sliding member describing upon rotation of said shaft substantially line contact, 'at least one dry lubricant member positioned in said support and spaced circumferentially from said sliding member, biasing means biasing said lubricant member 'against said shaft so that upon rotation of said shaft a film of lubricant is continually applied to said shaft and lightly burnished by said sliding member to provide a bearing.

5. The invention as recited in claim 3 wherein said cur'ved -surface is spherical.

6. The invention as recited in claim 3 wherein said curved surface is toroidal.

'7. The invention -as recited in claim 3 wherein said lubricant is a combination of M082 and AggS.

8. The invention as recited in claim 3 wherein said lubricant is va combination of M082 and SnS2.

9. A rotary sliding fbearing comprising in combination, an annular support member, a steel shaft positioned for rotation in said support member, a first steel sliding member in said support member having a spherica'l surface engaging said shaft, 'a second steel sliding member in said support member having 'a spherical surface engaging said shaft, said sliding member maintaining said shaft in spaced relationship to said support, said second member being circumferentially spaced from said first sliding member, a dry lubricant member in said support member spaced circumferentially from said first and second member, and biasing means biasing said lubricant against said shaft.

10. The invention as recited in claim 7 wherein a chrome surface is provided on said shaft to be engaged by said sliding members and said lubricant so that a film of dry lubricant is continually added to said chrome surface and continually burnished by said sliding elements.

11. The invention as recited in claim S wherein all circumferential spacing is each.

12. The invention as recited in claim 9, including biasing means biasing one of said sliding members against said shaft.

13. The invention as claimed in claim 10 wherein as ing said chrome surface on said 'shaf't, 'and engaging a dry 10 'lubricant in contact with 'said chrome to continually apply 'a film thereon while said steel member burnishes said film and supports the shaft for rotation.

References Citedl in 'the file of this patent UNITED sTArEs PAT'ENTS Faul Aug. 13, '1889 Faul 'May 26, 1914 Ulrich Oct. 10, 1933 Kinney Ju'ly 28, 1936 Schiffi June 27, 1944 Willis Aug, 10, 195.4

FOREIGN PATEN-TS Great Britain Aug. 26, 1943 Great lBritain M'ar. 3, 1954 Great Britain Apr. 7, 195,4

Great Britain j July 17, 1957 

